JPH0677147B2 - Lithographic printing original plate - Google Patents

Description

TECHNICAL FIELD The present invention relates to a lithographic printing original plate, and more particularly to a positive type lithographic printing original plate having high sensitivity (hereinafter abbreviated as positive type PS plate).

[Conventional technology]

At present, a positive PS plate is widely used in which an orthoquinonediazide compound and a phenol resin are coated on a grained hydrophilic aluminum support.

The orthoquinonediazide compound utilizes the property of being decomposed by irradiation with an actinic ray to generate a 5-membered ring carboxylic acid and being alkali-soluble, but has a drawback of insufficient sensitivity. This is because, in the case of the orthoquinonediazide compound, the quantum yield does not essentially exceed 1.

Although various attempts have been made so far to improve the sensitivity of a photosensitive composition containing an orthoquinonediazide compound, it has been extremely difficult to increase the sensitivity while maintaining the development tolerance during development. Examples of such attempts include the contents described in the specifications such as Japanese Patent Publication No. 48-12242, Japanese Patent Laid-Open No. 52-40125, and US Pat. No. 4,307,173.

Also, recently, some proposals have been made regarding a photosensitive composition which positively acts without using an orthoquinonediazide compound. As one of them, for example, Japanese Patent Publication No. Sho 56-269
Polymer compounds having an ortho-nitrocarbinol ester group described in the specification of No. 6 are mentioned. However, also in this case, the sensitivity cannot be said to be sufficient for the same reason as in the case of orthoquinone diazide. In addition to this, as a method of increasing sensitivity by using a photosensitive system which is activated by a contact action, there is known a known method in which an acid generated by photolysis causes a second reaction to solubilize an exposed area. The principle is applied.

As such an example, for example, a combination of a compound that generates an acid by photolysis with an acetal or an O, N-acetal compound (JP-A-48-89003), or a combination of an orthoester or an amide acetal compound (JP-A-58-89003) 51-120714
No.), a combination with a polymer having an acetal or ketal group in the main chain (JP-A-53-133429), a combination with an enol ether compound (JP-A-55-12995), a combination with an N-acyliminocarbonate compound. (JP-A-55-126236),
And a combination with a polymer having an orthoester group in the main chain (JP-A-56-17345). Since they have a quantum yield of more than 1 in principle, they may show high sensitivity. However, in the case of acetal or O, N-acetal compound, and in the case of a polymer having an acetal or ketal group in the main chain, light Since the second reaction rate due to the acid generated by decomposition is slow, the sensitivity is not sufficient for actual use.
Further, in the case of an orthoester or amide acetal compound, in the case of an enol ether compound, and in the case of an N-acyliminocarbonic acid compound, the sensitivity is certainly high, but the stability with time is poor and it cannot be stored for a long time. A polymer having an orthoester group in the main chain also has a high sensitivity but has a drawback that the development tolerance at the time of development is narrow.

In JP-A-58-224752, a water-resistant support is coated with a layer containing photocurable microcapsules, and the surface of the coated layer is subjected to pattern exposure, followed by pressurization and then lithographic printing. A method of obtaining a plate is disclosed. Although this method has high sensitivity in dry processing, this method utilizes the hydrophilicity of the microcapsule wall film and the lipophilicity of the photocurable resin, and the lithographic printing plate obtained has no hydrophilicity. Sufficient, easy to stain and low in printing durability. Further, there is a drawback that the lipophilicity of the photocurable resin is impeded by the hydrophilicity of the microcapsule wall film and the lipophilicity is insufficient so that the ink density does not increase.

[Problems to be solved by the invention]

Therefore, an object of the present invention is to provide a positive PS plate which has a high sensitivity, an excellent developing processability, a high printing durability, a high oil sensitivity, and a non-image area free from stains.

[Means for solving problems]

The object of the present invention is to provide a positive PS plate in which a layer containing a hydrophilic binder and a microcapsule containing a photopolymerizable monomer and / or a photosensitive resin and having a lipophilic wall film is provided on a hydrophilic support. Achieved by

The positive PS plate of the present invention can be image-formed by various methods. The microcapsule mainly encapsulating the photopolymerizable monomer and / or the photosensitive resin used in the present invention is hardened by light and softened, fused, melted, destroyed or encapsulated in the microcapsule even when heated or pressed. No material release occurs. On the other hand, the microcapsules in the unexposed area are stable during normal handling and under normal conditions, but they are softened, fused, melted, and destroyed by heating, and the microcapsule wall and / or inclusions in the microcapsules are mixed. Together they form a lipophilic uniform film. Further, the microcapsules are broken by the pressure, and the inclusions in the microcapsules are mixed with each other to form a lipophilic uniform film. Therefore, various methods are available for producing a printing plate from the positive PS plate of the present invention. That is, pattern exposure → heating → washoff → gumming, pattern exposure → heating → overall exposure → washoff → gumming,
Pattern exposure → Pressure → Whole surface exposure → Wash off → Gumming, thermal printing → Washoff → Gumming →, Thermal printing → Whole surface exposure → Washoff → Gumming, pressure printing → Whole surface exposure → Washoff → Gumming, ~, ~
In each of the above production methods, the microcapsules photocured on the printing machine are removed without washing off and gumming to form a non-image area. Further, the heating and the pressing may be used together with the pressing and the heating simultaneously or sequentially. When the heat treatment is used, the particle size of the microcapsules can be reduced, so that the image resolution is excellent, which is preferable. In addition, the method of removing the microcapsules photocured on the printing machine is
It is preferable because printing can be performed immediately without performing wash-off and gumming.

The lipophilic microcapsule wall advantageous for the present invention preferably has a contact angle with water of 40 degrees or more and is substantially water-insoluble. Examples of the constituent material of such a wall film include polyurethane, polyethylene, polyamide, polyester, polycarbonate, polyethyleneamine,
Phenol formalin resin, melamine resin, vinyl polymer and vinyl copolymer, polyacrylonitrile, polyvinyl acetal resin, cellulose acetate, polyethylene,
Examples include polypropylene and polybutadiene.

In order to obtain an image with high resolution, it is preferable to use a microcapsule having a small particle size (5 μm or less) and heat-bond the microcapsule having a heat-softening microcapsule wall by heating to form a lipophilic uniform film.

In this specification, the thermosoftening material means a material having a low glass transition temperature. If the glass transition temperature of the microcapsule wall is low, it softens at a low temperature. Glass transition temperature is 60
It is effective to be in the range of ℃ to 300 ℃, the preferred range is 70 ℃ ~ 250 ℃, more preferably 80 ℃ ~ 220 ℃ range. The glass transition temperature here is measured as follows.

Vibron DDV-II type (manufactured by Toyo Baldwin Co., Ltd.)
The dynamic storage elastic modulus (E ′) and the dynamic loss elastic modulus (E ″) of the sample film are measured by using the tan δ = E ′ / E ″ and the temperature at which the peak tan δ is obtained is determined by the glass transition. Temperature.

The heating rate at this time is 2 ° C / min. When the glass transition temperature is low, stability with time is poor, and when the glass transition temperature is high, heating at a high temperature causes the support to be deformed and stains during printing, which is not preferable. The wall material of the microcapsule is preferably polyurea, polyurethane, polyester, polycarbonate or polyamide, and particularly preferably polyurea or polyurethane.

The microcapsules used in the present invention can be produced by a method known in the art. For example, U.S. Pat.No. 3,287,154,
British Patent No. 990,443, Japanese Patent Publication No. 38-19574, 42-446
No. 42-711 interfacial polymerization method, U.S. Pat.Nos. 3,418,250, 3,660,304 polymer precipitation method, U.S. Pat.No. 3,796,669 using isocyanate polyol wall material , U.S. Pat.No. 3,914,511, using the isocyanate wall material, U.S. Pat.Nos. 4,001,140, 4,087,376 and 4,089,802 using urea-formaldehyde-based or urea formaldehyde-resorcinol-based wall forming material U.S. Pat. No. 4,025,455, a method of using a wall forming material such as melamine-formaldehyde resin and hydroxypropyl cellulose, JP-B-36-916.
No. 3, by polymerization of monomers found in JP-A-51-9079
The in situ method, the electrolytic dispersion cooling method seen in British Patent Nos. 952,807 and 965,074, and the spray drying method seen in U.S. Pat. No. 3,111,407 and British Patent 930,422 are available. Although not limited thereto, it is preferable to form a polymer film as a microcapsule wall after emulsifying the core substance.

The particle size of the microcapsules is preferably adjusted to 30 μm or less, 0.01 μm or more, particularly preferably 10 μm or less from the viewpoint of handleability, and particularly preferably 5 μm or less from the viewpoint of pattern resolution.

The polymerizable monomer referred to in the present invention is a compound having one or more vinyl or vinylidene groups, preferably a plurality of groups, for example, an acryloyl group, a methacryloyl group, an allyl group,
Examples thereof include compounds having an unsaturated polyester group, vinyloxy group, acrylamide group and the like. The most representative ones are reaction products of unsaturated carboxylic acids with polyols, polyamines or amino alcohols, reaction products of acrylates or methacrylates having a hydroxyl group with polyisocyanates, and the like.

For example, as typical compounds, polyethylene glycol diacrylate, propylene glycol dimethacrylate, pentaerythritol triacrylate, trimethylolproopane diacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, hexanediol diacrylate, 1,2-
Butanediol diacrylate, tetrakis β-acryloxyethyl ethylenediamine, reaction product of epoxy resin and acrylic acid, reaction product of methacrylic acid and pentaerythritol and acrylic acid, condensate of maleic acid and diethylene glycol and acrylic acid, methyl methacrylate,
Butyl methacrylate, styrene, divinylbenzene,
Examples include diarylnaphthalene. Regarding these monomers, JP-A-49-52889, JP-A-48-68641, and JP-A-48-32586
It can also be selected from those disclosed in Japanese Patent Publication No. 49-7115. These may be used in combination according to the purpose.

Since these monomers usually have absorption in the ultraviolet region of 300 nm or less, it is advisable to use a photosensitive substance that absorbs the ultraviolet to visible light and imparts photosensitivity to the ultraviolet to visible light source, and polymerizes the monomer. desirable. An example thereof is one generally known as a photopolymerization initiator, which is already described in detail in a book, for example, Kosar “Light Sensitine Systems” J.
Ohn Wiley & Sons), Warashina et al. “Photosensitive Resin” Nikkan Kogyo Shimbun, Tsunoda et al. “Photosensitive Resin” Printing Society, etc.

Specific examples of the photopolymerization initiator include aromatic ketones, quinone compounds, ether compounds and nitro compounds.

Specifically, benzoquinone, phenanthrenequinone, naphthoquinone, diisopropylphenanthrenequinone, benzoisobutyl ether, benzoin, furoin butyl ether, Michler's ketone, Michler's thioketone, tetraphenyl lophine dimer, fluorenone, trinitrofluorenone, β- Benzoylaminonaphthalene and the like are included.

These are added to the vinyl compound in an amount of 0.1% to 30%.

Furthermore, in order to efficiently carry out curing by photopolymerization, Japanese Patent Application No. 60
-151864, Japanese Patent Publication No. 46-32714, Japanese Patent Publication No. 49-34
The polymer described in Japanese Patent No. 041 can be contained in microcapsules.

When encapsulating the above polymerizable monomer, photopolymerization initiator, photosensitive resin, etc., dissolution can be used together. As the solvent, natural or synthetic oils can be used alone or in combination. Examples of the solvent include cottonseed oil, kerosene, aliphatic ketone, aliphatic ester, paraffin, naphthene oil, alkylated biphenyl, alkylated terphenyl, chlorinated paraffin, alkylated naphthalene, 1-phenyl-1-xylylethane, 1- Phenyl-1-p-
Examples thereof include diarylethane such as ethylphenylethane and 1,1′-ditolylethane.

Further, as the photosensitive resin, a cinnamic acid ester of polyvinyl alcohol, a photosensitive compound composed of an azide compound and a cyclized rubber, or a styrene-butadiene copolymer, a diazo photosensitive resin, a photosensitive resin composed of polyvinylacetophenone and benzaldehyde. Etc.

In addition to the above, a thermal polymerization inhibitor may be further added. For example, hydroquinone, p-methoxyphenol,
Di-t-butyl-p-cresol, pyrogallol, t-
Butylcatechol, benzoquinone, 4,4'-thiobis (3-methyl-6-t-butylphenol), 2,2'-
Methylenebis (4-methyl-6-t-butylphenol), 2-mercaptobenzimidazole and the like are useful. Further, for the purpose of coloring the photosensitive layer, a dye or pigment, a pH indicator as a printing agent, and a dye described in JP-A-60-120354 can be contained in the microcapsules.

Further, in order to color the image portion, at least one of a photo-curable microcapsule color-forming agent or a color-developing agent which comes into contact with the color-forming agent to generate a coloring substance can be contained. The color former has a property of developing a color by donating electrons or accepting a proton such as an acid, and is not particularly limited, but it is usually almost colorless, and lactone, lactam, sultone, spiropyran, ester, amide. A compound having a partial skeleton such as, for example, which is opened or cleaved by contact with a color developer is used. Specific examples include crystal violet lactone, benzoyl leuco methylene blue, malachite green lactone, rhodamine β-lactam, and 1,3,3-trimethyl-6′-ethyl-8′-butoxyindolinobenzospiropyran.

Phenol compounds, organic acids or metal salts thereof, oxybenzoic acid esters, clays and the like are used as developers for these color formers.

In particular, the melting point is 50 ° to 250 ° C, particularly preferably 60 ° to 2
Phenols and organic acids that are sparingly soluble in water at 00 ° C are desirable.

Examples of phenol compounds are 4,4'-isopropylidene-diphenol (bisphenol A), p-tert-
Butylphenol, 2,4-dinitrophenol, 3,4-dichlorophenol, 4,4'-methylene-bis (2,6-di-
tert-butylphenol), p-phenylphenol,
4,4-Cyclohexylidenediphenol, 2,2'-methylenebis (4-tert-butylphenol), 2,2'-methylenebis (α-phenyl-p-cresol) thiodiphenol, 4,4'-thiobis (6 -Tert-butyl-m-cresol), sulfonyldiphenol, 1,1-bis (4
-Hydroxyphenyl) -n-dodecane, 4,4'-bis (4-hydroxyphenyl) -1-pentanoic acid ethyl ester, p-tert-butylphenol-formalin condensate, p-phenylphenolformalin condensate, etc. is there.

As the organic acid, 3-tert-butylsalicylic acid, 3,5-t
ert-butylsalicylic acid, 5-α-methylbenzylsalicylic acid, 3,5-di-α-methylbenzylsalicylic acid, 3
-Tert-octylsalicylic acid, 5-α, γ-dimethyl-
α-Phenyl-γ-phenylpropylsalicylic acid and the like are useful.

Examples of the oxybenzoic acid ester include ethyl p-oxybenzoate, butyl p-oxybenzoate, heptyl p-oxybenzoate, benzyl p-oxybenzoate and the like.

Further, a foaming agent can be contained in the photo-effect microcapsules in order to effectively mix the contents of the capsules by heating.

As the foaming agent, nitroso compounds, sulfohydrazide compounds which are hydrazine derivatives of organic sulfonic acid, hydrazo compounds and azo compounds can be used.

Specific examples of the organic foaming agent include dinitrosopentamethylenetetramine, N, N'-dimethyl-N, N'-dinitrosoterephthalamide, and trinitrosotrimethylenetriamine as nitroso compounds.

The sulfohydrazide compounds include p-toluenesulfohydrazide, benzenesulfohydrazide, p, p'-
Oxybis (benzenesulfohydrazide), benzene-
1,3-disulfohydrazide, 3,3'-disulfohydrazide phenyl sulfone, toluene-2,4-disulfohydrazide, p, p'-thiobis (benzenesulfohydrazide)
Etc. Examples of the hydrazo compound include hydrazodicarboxamide, N, N'-dibenzoylhydrazine, β-acetylphenylhydrazine, bayurea, and 1,1-diphenylhydrazine.

Examples of the azo compound include azobisisobutyronitrile, azodicarbonamide (azobisformamide), diazoaminobenzene, and azocarboxylic acid diethyl ester (diethylazodicarboxylate).

All of these organic foaming agents decompose by heating to generate nitrogen gas. In addition to nitrogen gas, some compounds generate some carbon monoxide, carbon dioxide, and water vapor, but at least 60% of the generated gas is nitrogen gas. The amount of generated gas is generally 100 to 300 ml / g.

The thermal decomposition temperature of these organic foaming agents ranges from about 80 ° C to about 300 ° C.

A thermal decomposition aid can also be used in the present invention to lower the decomposition temperature of the organic blowing agent.

As the thermal decomposition aid, urea and urea derivatives, zinc white,
Lead carbonate, lead stearate, glycolic acid, etc. are effective. Among these, urea and urea derivatives such as urea ethanolamine, guanylurea, aminoguanidine carbonate and the like are particularly preferable. The amount of the thermal decomposition aid added is preferably about 30 to 60% by weight based on the organic foaming agent.

For example, the decomposition temperature of a pure chemical product of azodicarbonamide is said to be 230 ° C, but it can be lowered to about 120 ° C by adding various thermal decomposition auxiliary agents.

Water-soluble polymers and surfactants can be used for emulsion dispersion when making capsules. Water-soluble polymers include water-soluble anionic polymers, nonionic polymers, and amphoteric polymers. the sex polymer can be used even as be of natural or synthetic, for example -COO ^-, -SO
Those having a ₃ ^- group and the like can be mentioned. Specific examples of anionic natural polymers include gum arabic and alginic acid, and semi-synthetic products include carboxymethyl cellulose and
Examples include phthalated gelatin, sulfated starch, sulfated cellulose and lignin sulfonic acid.

Further, synthetic products include maleic anhydride-based (including hydrolyzed) copolymers, acrylic acid-based (including methacrylic acid-based) polymers and copolymers, vinylbenzenesulfonic acid-based polymers and copolymers, Examples include carboxy-modified polyvinyl alcohol.

Examples of amphoteric compounds include gelatin.

Nonionic surface active agents such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and glycerin fatty acid esters as surfactants Agents such as fatty acid salts, alkyl sulfate ester salts, alkylbenzene sulfonates, alkylnaphthalene sulfonates, dialkylsulfosuccinic acid ester salts, alkyl phosphoric acid ester salts, naphthalene sulfonic acid formalin condensates, polyoxyethylene alkyl sulfate ester salts, etc. Anionic surfactants, and, for example, alkylamine salts, quaternary ammonium salts,
Examples thereof include cationic surfactants such as polyoxyethylene alkylamine salts, and fluorine-based surfactants. These dispersion stabilizers may be used alone or in combination of two or more.

As an emulsifying device used for emulsifying and dispersing, a device that gives a large shearing force to the treatment liquid or a device that gives high-intensity ultrasonic energy is suitable. In particular, a colloid mill, a homogenizer, a capillary type emulsifying device, a liquid siren, an electromagnetic distortion type ultrasonic generator, and an emulsifying device having a Paulman whistle can give good results.

The hydrophilic binders referred to in the present invention can be used alone or in combination. As a hydrophilic binder, a transparent or translucent hydrophilic binder is typical,
For example, gelatin, gelatin derivatives, carboxymethylcellulose, cellulose derivatives such as methylcellulose,
Natural substances such as polysaccharides such as starch and arabic gum, and synthetic polymers such as water-soluble polyvinyl compounds such as polyvinyl alcohol, polyvinylpyrrolidone, acrylamide polymer, polyacrylic acid, vinyl acetate-acrylic acid copolymer, etc. Including.

As the support, various hydrophilically treated materials can be used. Paper, paper laminated with plastics (eg polyethylene, polypropylene, polystyrene, etc.), aluminum (including aluminum alloys),
Metal plates such as zinc, iron, copper, cellulose acetate,
Films of plastics such as cellulose propionate, cellulose butyrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal and the like, papers or plastic films on which the above metals are laminated or vapor deposited, and the like. These supports may be subjected to surface roughening treatment if necessary.

For example, an aluminum support is surface-treated as follows. Electrochemical graining method in which electricity is applied to an aluminum plate in, for example, hydrochloric acid or nitric acid electrolyte to grain it, and a wire brush grain method in which the aluminum surface is scratched with a metal wire, and the aluminum surface is grained with abrasive balls and an abrasive Graining is performed using a ball graining method, a mechanical graining method such as a brush graining method in which the surface is grained with a nylon brush and an abrasive, alone or in combination.

Thus, the grained aluminum is chemically etched by acid or alkali. When an acid is used as an etching agent, it takes a very long time to destroy the fine structure, which is disadvantageous in industrial application, but it can be improved by using an alkali as the etching agent.

Alkali agents preferably used for these purposes are caustic soda, sodium carbonate, sodium aluminate, sodium metasilicate,
Using sodium phosphate, potassium hydroxide, lithium hydroxide, etc., the preferred ranges of concentration and temperature are 1 to 50 weight 5 and 20 to 100 ° C, respectively, so that the amount of Al dissolved is 5 to 20 g / m ^2. Different conditions are preferred.

After alkali etching, pickling is performed to remove stains (smut) remaining on the surface. As the acid used, nitric acid, sulfuric acid, phosphoric acid, chromic acid, hydrofluoric acid, hydrofluoric acid, etc. are used.

Further, for the smut removal treatment after the electrochemical surface roughening treatment, it is preferable to use 15 to 65% by weight of sulfuric acid at a temperature of 50 to 90 ° C. as described in JP-A-53-12739. The contacting method and the alkali etching method described in JP-B-48-28123.

Although the aluminum plate treated as described above can be used, it can be further subjected to treatments such as anodizing treatment and chemical conversion treatment.

The anodizing treatment can be performed by a method conventionally used in this field. Specifically, sulfuric acid, phosphoric acid,
Chromic acid, oxalic acid, sulfamic acid, benzenesulfonic acid, etc., or an aqueous solution containing a combination of two or more of these, or by applying a direct current or an alternating current to aluminum in an aqueous solution, an anodized film can be formed on the surface of the aluminum support. .

The treatment conditions for anodic oxidation cannot be unconditionally determined because it varies depending on the electrolytic solution used, but generally the concentration of the electrolytic solution is 1 to 80% by weight, the liquid temperature is 5 to 70 ° C, and the current density is 0.5.
Appropriate ranges are -60 amperes / dm ² , voltage 1-100 V, and electrolysis time 10-100 seconds.

Among these anodic oxide film treatments, especially British Patent No. 1,
The method of anodizing in sulfuric acid at a high current density and the method of anodizing phosphoric acid as an electrolytic bath described in U.S. Pat.No. 3,511,661 used in the invention described in 412,768 are described. preferable.

Anodized aluminum plates are further described in US Pat.
No. 4,066,3,181,461, it is treated by a method such as dipping in an aqueous solution of an alkali metal silicate, for example, sodium silicate as described in US Pat.
An undercoat layer of hydrophilic cellulose (eg, carboxymethyl cellulose, etc.) containing a water-soluble metal salt (eg, zinc acetate, etc.) can also be provided as described in 3,860,426.

When applied to a support, a filler such as talc powder, glass powder, clay, starch, wheat flour, corn powder, Teflon powder, or polyethylene powder may be added to improve vacuum adhesion during pattern baking. .

Further, various additives, binders, antioxidants, dispersants, defoamers, pigments, dyes, surfactants, coating methods, and usage methods conventionally used in recording systems are well known. Patents 2,711,375, 3,625,736, British patent
1,232,347, JP-A-50-44012, 50-50112, 50-
127718, 50-30615, U.S. Pat. Nos. 3,836,383, 3,846,331 and the like, and these techniques can be used.

A protective layer or matte layer may be provided to control the physical properties of the surface of the PS plate.

The positive PS plate prepared as described above is exposed to actinic rays. Examples of the light source of actinic rays include a mercury lamp, a metal halide lamp, a xenon lamp, a chemical lamp, and a carbon arc lamp. Scanning exposure with a high-density energy beam (laser beam or electron beam) can also be used in the present invention. Examples of such a laser beam include a helium / neon laser, an argon laser, a krypton ion laser, and a helium / cadmium laser.

Also, thermal printing can be performed. For thermal printing, a thermal printer such as a thermal printer or a thermal facsimile used as a terminal of a word processor is used.
As a heating device used for heating after pattern exposure, for example, a method of heating while contacting the photosensitive surface with a heating roller having a heater, a method of contacting with a hot plate, a ribbon heater, a sheath heater, an infrared heater, or other heat source. The plate is heated near the plate surface during transportation, the method of blowing heated air, the method of immersing or contacting in a heating liquid, and the method of directly heating the plate and self-heating by irradiation of electron beam, high frequency, and other electromagnetic waves Methods etc. can be used.

The heating temperature and time are determined by the wall material of the microcapsule, the wall thickness, the type of inclusions in the microcapsule such as the photopolymerizable monomer, and the photosensitive resin, and are limited to specific values. 60 ℃ to 30 ℃
The range of 0 ° C is effective, and the preferred range is 70 ° C to 250 ° C.
More preferably, it is in the range of 80 ° C to 220 ° C. It is difficult to obtain a uniform lipophilic film at 60 ° C or lower, and there is a risk of fouling at 300 ° C or higher. A heating time of 1/20 to 20 minutes is effective, but a preferable range is 1/15 to 15 minutes, more preferably 1/10 to 10 minutes.

When pressurizing, it can be easily performed by passing between two rolls. When both heating and pressurizing are used, it can be carried out by passing through two rolls having a built-in heater, or immediately after heating or by passing between two rolls in a heating zone. . The applied pressure is not limited to a specific numerical value, but is practically preferably about 500 kg / cm ² or less.

The lithographic printing plate obtained according to the present invention may be subjected to lipophilic treatment for the purpose of further improving printability. As the treatment liquid used for the lipophilic treatment, there is a treatment liquid mainly composed of a polymer having a hydrophilic group or a metal salt thereof.

〔Example〕

Examples of the present invention will be shown below, but the present invention is not limited thereto.

Example 1 (1) A support was prepared as follows.

A substrate was prepared by the method disclosed in JP-A-56-28893. That is, using a 0.24 mm thick aluminum plate with a nylon brush and 400 mesh pumicestone water suspension,
The surface was grained and then thoroughly washed with water. Then
It was immersed in 10% sodium hydroxide at 50 ° C. for 60 seconds for etching, washed with running water, neutralized with 20% HNO ₃ and washed with water. Using an alternating waveform current of sine wave under the condition that the voltage at the anode is 12.7 V and the ratio of the electricity at the cathode to the electricity at the anode is 0.8, the electricity at the anode of 160 clones / dm ² in 1% nitric acid aqueous solution is used. The amount of electrolytic roughening treatment was performed. The surface roughness at this time was measured and found to be 0.6 μ (Ra display). Subsequent immersion in 30% sulfuric acid and desmutting at 55 ° C for 2 minutes, then in 20% sulfuric acid at a current density of 2 A / dm ² , the thickness was 2.
Anodizing treatment was performed so as to obtain 7 g / dm ² . After that, it was immersed in a 2.5% aqueous solution of sodium silicate at 70 ° C. for 1 minute, washed with water and dried.

(2) Next, a photosensitive solution was prepared as follows.

Dissolve 2,2-dimethoxy-2-phenylacetophenone 5 g in trimethylolpropane triacrylate 40 g,
Furthermore, 15 g of Takenate D110N (manufactured by Takeda Pharmaceutical Co., Ltd.) was dissolved and mixed to obtain an oil phase.

This oil phase was emulsified and dispersed in 70 g of a 2% polyvinyl alcohol PVA-205 (Kuraray Co., Ltd.) aqueous solution. Diethylenetriamine 1.67% aqueous solution while stirring this emulsion at room temperature
20 g was added and subsequently stirred. After 30 minutes, raise the temperature to 40 ° C,
After stirring for another 1 hour, the mixture was cooled. The average particle size of the obtained microcapsules was 2.1μ.

(3) 100 g of water in 50 g of the microcapsule solution thus obtained,
1 g of white dextrin (manufactured by Nippon Starch Chemical Co., Ltd.) was added to obtain a photosensitive solution. The above aluminum support was coated so that the coating weight after drying was 3.5 g / m ² , and dried to obtain a positive PS plate.

(4) Next, as a comparative example, the following photosensitive solution was applied to the above support and dried at 100 ° C. for 2 minutes. The coating weight was 2.3 g / m ² .

Photosensitive liquid (5) A gray scale with a density difference of 0.15 was brought into close contact with the positive PS plates of the examples and comparative examples, and exposure was performed from a distance of 1 m 40 cm with a carbon arc lamp of 30 amperes.

In the case of Example 1, the positive PS plate exposed to show the excellent sensitivity of the present invention was heated at 180 ° C. for 1 minute after exposure and washed off with water using a sponge, and in the case of Comparative Example. DP
-4 [Product name: Fuji Photo Film Co., Ltd.] dip-developed with a 10 times diluted aqueous solution at 25 ° C for 60 seconds to obtain an exposure time at which the 5th step is completely clear in a Grace case with a density difference of 0.15. As a result, the results shown in Table 1 were obtained.

As can be seen from Table 1, the positive PS plate of the present invention (Example 1) has significantly less exposure time than Comparative Example 1 and high sensitivity.

When these were attached to a Heidelberg GTO type printing machine and printed, both prints without stains were obtained.

Example 2 (1) A photosensitive solution was prepared as follows.

Trimethylolpropane triacrylate 30g, 2,2-dimethoxy-2-phenylacetophenone 3g, Vernock
DN950 (manufactured by Dainippon Ink and Chemicals, Inc.) (15 g) was mixed to obtain an oil phase.

This oil phase was emulsified and dispersed in a 2% aqueous solution of methyl cellulose. This emulsion was stirred at room temperature, 10 g of a 1.67% aqueous solution of diethylenetriamine was added, and the mixture was continuously stirred. 30
After a minute, the temperature was raised to 40 ° C., and the mixture was further stirred for 30 minutes and cooled. The average particle size of the obtained microcapsules was 2.4μ.

(2) The microcapsule solution thus obtained was coated on the aluminum support described in Example 1 so that the coating weight after drying was 4.2 g / m ² and dried to obtain a positive PS plate.

(3) A positive film is placed on this positive PS plate, and they are vacuum-bonded to each other, and made by Nuark ET26V UDNS ULTRA-PLUS FLIP-TOP P
After exposure by LATE MAKER, the plate was heated in an air constant temperature bath at 150 ° C. for 1 minute, and the whole surface was exposed again to obtain a lithographic printing plate.

(4) As Comparative Example 2, a lithographic printing plate was obtained according to the method of Example 1 described in JP-A-58-224752.

(5) When these were mounted on a Heidelberg GTO type printing machine and printed, the non-image area was smeared after printing 500 sheets in Comparative Example 2, but in the example of the present invention, 1,000 or more unstained printed matters were obtained. Was obtained.

Claims (1)

[Claims] 1. A positive planographic printing plate comprising a hydrophilic support and a layer containing microcapsules containing a photopolymerizable monomer and / or a photosensitive resin and having a lipophilic wall film, and a hydrophilic binder. Original printing plate.